Certain carbonaceous products of sugar fermentation are seen as replacements for petroleum-derived materials for use as feedstocks for the manufacture of carbon-containing chemicals. One such product is MAS.
A material related to MAS, namely SA, can be produced by microorganisms using fermentable carbon sources such as sugars as starting materials. However, most commercially viable, succinate producing microorganisms described in the literature neutralize the fermentation broth to maintain an appropriate pH for maximum growth, conversion and productivity. Typically, the pH of the fermentation broth is maintained at or near a pH of 7 by introduction of ammonium hydroxide into the broth, thereby converting the SA to diammonium succinate (DAS). The DAS may be converted to MAS to derive MAS from the fermentation broth.
Kushiki (Japanese Published Patent Application, Publication No. 2005-139156) discloses a method of obtaining MAS from an aqueous solution of DAS that could be obtained from a fermentation broth to which an ammonium salt is added as a counter ion. Specifically, MAS is crystallized from an aqueous solution of DAS by adding acetic acid to the solution to adjust the pH of the solution to a value between 4.6 and 6.3, causing impure MAS to crystallize from the solution.
Masuda (Japanese Unexamined Application Publication P2007-254354, Oct. 4, 2007) describes partial deammoniation of dilute aqueous solutions of “ammonium succinate” of the formula H4NOOCCH2CH2COONH4. From the molecular formula disclosed, it can be seen that “ammonium succinate” is diammonium succinate. Masuda removes water and ammonia by heating solutions of the ammonium succinate to yield a solid SA-based composition containing, in addition to ammonium succinate, at least one of MAS, SA, monoamide succinate, succinimide, succinamide or ester succinate. Thus, it can be inferred that like Kushiki, Masuda discloses a process that results in production of impure MAS. The processes of both Kushiki and Masuda lead to materials that need to be subjected to various purification regimes to produce high purity MAS.
Bio-derived MAS and SA such as that derived from MAS itself are platform molecules for synthesis of a number of commercially important chemicals and polymers. Therefore, it is highly desirable to provide a purification technology that offers flexibility to integrate clear, commercially viable paths to derivatives such as DAB, SDN and DAM. In response to the lack of an economically and technically viable process solution for converting fermentation-derived SA/MAS to DAB, SDN, succinic amino nitrile (SAN) and DAM, it could be helpful to provide methods for providing a cost effective SA/MAS stream of sufficient purity for direct hydrogenation.